Exploring Proposition 36 as a Turning Point in Life Course Drug Use Trajectories Abstract Rooted in the life course theory, the idea of turning points has been used to explain and characterize major changes in drug use trajectories (Hser et al., 2007b). Developmental transitions (e.g., into adolescence, or adulthood) and critical life events (e.g., employment, marriage, military service) are a few examples that have been cited as turning points, which modify life trajectories and redirect pathways. Yet, the same life event may trigger a turning point for some individuals, but not for others, and knowledge about the developmental processes and underlying mechanisms involved in turning points of drug use trajectories is limited. The applicants propose to explore whether and how California's Proposition 36 (or Prop 36, aka the Substance Abuse and Crime Prevention Act) served as a turning point redirecting participants'drug use trajectories. This relatively new law offers adults convicted of nonviolent drug possession offenses the opportunity to choose drug treatment in the community in lieu of incarceration or probation without treatment. While the statewide evaluation has generally shown positive treatment outcomes among Prop 36 clients, little is known about whether and how Prop 36 has impacted individuals'drug use trajectories in the long run. By conducting in-depth qualitative interviews (n = 80) with selected Prop 36 participants from another NIDA-supported study of outcomes among clients enrolled in treatment (some of whom have sustained abstinence since entering treatment under Prop 36 and others who have not), the proposed study will explore if Prop 36 has served as a turning point for these individuals and describe related subjective experiences. While we are particularly interested in what role Prop 36 may have played in participants'drug use, we seek to uncover what other experiences, events, and processes may also have contributed to the change or lack of change in drug use trajectories. Our goal for this exploratory study is to derive theory components that may account for the underlying mechanisms and developmental processes involved in turning points within the life course of drug use and to generate hypotheses to test in future research studies via the R01 grant mechanism. The ultimate objective of this series of studies is to develop and test interventions and strategies to improve outcomes for substance users. PUBLIC HEALTH RELEVANCE: Exploring Proposition 36 as a Turning Point in Life Course Drug Use Trajectories Project Narrative The knowledge and information gained from this exploratory study will be used to improve public health by deriving theory to account for the underlying mechanisms and developmental processes involved in turning points of the life course of drug use and to generate hypotheses to test in future research studies via the R01 grant mechanism. The ultimate objective of this series of studies is to develop and test interventions and strategies to improve outcomes for substance users.